Amelogenesis imperfecta - Causes, Symptoms, Features and Diagnosis

Introduction:

The teeth in our oral cavity start budding at six months of age, and they are replaced with permanent teeth by the age of 6 to 7 years. The teeth are covered by a protective and shiny layer called enamel, and several enzymes and proteins are involved in enamel formation (amelogenesis). Unfortunately, the whole amelogenesis process is disturbed by a genetic condition leading to improper enamel formation. This article illustrates the causes and clinical features of amelogenesis imperfecta.

What Is Amelogenesis Imperfecta?

Amelogenesis imperfecta refers to an inherited disorder that causes defective enamel formation. Both milk teeth and permanent teeth are affected. Finn was the first to describe amelogenesis imperfecta in 1938. Several studies show that the occurrence of amelogenesis imperfecta is one in 700 to one in 14,000.

What Causes Amelogenesis Imperfecta?

The main reason behind amelogenesis imperfecta is genetic changes (mutations). Genes like AMELX, MMP20, ENAM, etc., are responsible for commanding the protein production that aids in enamel formation. The children acquire the condition from their parents. The chance of getting the abnormal gene is high if the parents are close relatives (consanguineous marriage).

How Is Amelogenesis Imperfecta Classified?

There are various classification systems of amelogenesis imperfecta, the one described by Winter and Brook in 1975 is as follows:

• Type I - Hypoplastic refers to a defect in the enamel amount.

• Type II - Hypomaturation refers to defective enamel development and maturation.

• Type III - Hypocalcified refers to the defective mineralization of tooth enamel.

• Type IV - Hypomaturation-hypoplasia with taurodontism (change in tooth shape).

What Are the Symptoms of Amelogenesis Imperfecta?

The outer protective layer called enamel is either defective or not formed in the case of amelogenesis imperfecta. The clinical features are as follows:

• Yellow or brownish discoloration of teeth.

• Early tooth loss.

• Tooth decay.

• Cracked tooth.

• Sensitive tooth due to dentin exposure (sensitive layer behind the enamel), as the enamel erodes.

• Pain occurs if the inner pulp tissue is exposed.

What Are the Characteristic Features of Different Types?

• Type I - The hypoplastic type is the most common and shows different features in males and females as follows,

• In Men: The enamel looks thin, clear, and with standard color. In a few others, the enamel looks discolored (yellow or brown), less mineralized but with average thickness. The teeth may be sensitive to hot or cold foods.

• In Women: Vertical ridges or depressions may be present. In addition, vertical bands of normal and discolored enamel are observed in certain conditions.

• Type II -

• The tooth surface looks rough.

• The upper and lower teeth do not occlude properly, leading to an open bite.

• The enamel thickness may be thin or regular but tends to break.

• The color of the teeth may range from creamy white to yellow and brown.

• Type III -

• Open bite.

• The features are similar to that of the hypomaturation type.

• Type IV -

• The teeth look relatively smaller.

• The spotted appearance of teeth.

• The enamel is less mineralized and looks pitted.

• The teeth look yellow or brown.

How to Diagnose Amelogenesis Imperfecta?

• Intra-Oral Examination - The dentist examines the teeth pitting, spotting or ridges, and discoloration. The doctor may enquire about the family history to decide on further investigations and treatment.

• Radiographic Examination - The dentist orders the extraoral and intraoral radiographs to view the teeth that have not erupted and determine the mineralization level.

• Genetic Testing aids in evaluating the mutations in specific genes responsible for causing amelogenesis imperfecta.

What Other Conditions Resemble Amelogenesis Imperfecta?

• Dental Fluorosis - The prolonged fluoride consumption in any form (toothpaste, fluoridated drinking water) during tooth development results in dental fluorosis. It is characterized by white streaks or brown stains on the affected teeth. The dentist may suggest treatments like crowns, restorations, etc., to improve the tooth appearance.

• Tricho-Dento-Osseous Syndrome is an inherited disorder that affects the teeth, hair, and bone. The affected tooth looks small, discolored, and with decreased thickness. Other features include bony changes, protruding lower jaw, curly hair, and nail defects.

Can Amelogenesis Imperfecta Be Corrected?

There is no complete cure for amelogenesis imperfecta; however, specific supportive treatments are followed depending on the individual’s age and severity. It involves:

• Crown - The dental caps or crowns aid in restoring the shape and protecting the tooth structure. They are available for both the front and back teeth and in different materials (metal, ceramic, porcelain fused with metal, etc). In younger children, the dentist may suggest metal crowns for the teeth at the back and polycarbonate crowns for the front teeth to improve esthetics. After six years, when the permanent tooth erupts, it becomes difficult to maintain oral hygiene and restore the teeth. The dentist may fix preformed crowns to the teeth under local anesthesia.

• Restorations - Composite restorations are mostly preferred for the anterior teeth to mimic the enamel and dentin of the teeth. It aids in masking the enamel defects and provides structure to the teeth.

• Orthodontic Treatment - The orthodontist also suggests certain oral appliances that treat malocclusion in children, especially the open bite.

• Oral Hygiene Instructions - Maintaining good oral hygiene in children with amelogenesis imperfecta becomes difficult for the parents. The dentist may suggest using desensitizing toothpaste or gels for sensitive teeth.

• Genetic Counseling - The affected parents should be informed about the risk of the child acquiring amelogenesis imperfecta and the essential measures to be followed to maintain the tooth structure.

• Supportive Care - Many affected individuals may stay alone and look depressed due to the unesthetic appearance of their teeth. They may use several items like paper or chewing gums to mask their teeth’s look. Therefore, they are prone to mental illness. It is the responsibility of the dentist to provide hope to the individual affected with amelogenesis imperfecta.

What Is the Complication Related to Amelogenesis Imperfecta?

Without proper enamel, the teeth are prone to break or to get damaged, along with gum disease and tooth decay. People with this condition must regularly visit the dentist for cleaning and other checkups. Few people can face emotional imbalance as this condition affects the tooth's appearance.

Conclusion:

Amelogenesis imperfecta is a rare disorder, but it dramatically affects the esthetics and function of the teeth. The affected children and adults are incredibly stressed due to their unappealing appearance. Therefore, it is the responsibility of the healthcare specialist to provide counseling that improves their mental health and encourages them to maintain their oral health.